This disclosure is directed to components for the interior of trains, and in particular seat components and claddings having low smoke density and low heat release.
Standards for flame retardancy properties such as flame spread, heat release, and smoke generation upon burning have become increasingly stringent for articles used in mass transportation such as trains. The European Union has approved the introduction of a new harmonized fire standard for rail applications, namely EN-45545, to replace all currently active different standards in each member state. This standard imposes stringent requirements on heat release, smoke density, and toxicity and flame spread properties allowed for materials used in these applications. Smoke density (Ds-4) in EN-45545 is the smoke density after four minutes measured according to ISO 5659-2, and heat release in EN-45545 is the maximum average rate of heat emission (MAHRE) measured according to ISO5660-1 and flame spread in EN-45545 is the critical heat flux at extinguishment (CFE) measured according to ISO 5658-2.
“Hazard Levels” (HL1 to HL3) have been designated, reflecting the degree of probability of personal injury as the result of a fire. The levels are based on dwell time and are related to operation and design categories. HL1 is the lowest hazard level and is typically applicable to vehicles that run under relatively safe conditions (easy evacuation of the vehicle). HL3 is the highest hazard level and represents most dangerous operation/design categories (difficult and/or time-consuming evacuation of the vehicle, e.g. in underground rail cars). For each application type, different test requirements for the hazard levels are defined.
For R6 applications, covering seat components, requirements on smoke density after four minutes measured according to ISO 5659-2 (Ds-4) are Ds-4 values at or below 300 measured at 50 kW/m2 for HL2 and at or below 150 measured at 50 kW/m2 for HL3. Requirements on the maximum average rate of heat emission (MAHRE) measured according to ISO5660-1 are at or below 90 kW/m2 determined at 50 kW/m2 for HL2 and at or below 60 kW/m2 determined at 50 kW/m2 for HL3. For R6 applications, no requirements on flame spread measured according to ISO 5658-2 exist.
Typical applications falling under R1 applications include interior vertical surfaces, such as side walls, front walls, end-walls, partitions, room dividers, flaps, boxes, hoods and louvres; interior doors and linings for internal and external doors; window insulations, kitchen interior surfaces, interior horizontal surfaces, such as ceiling paneling, flaps, boxes, hoods and louvres; luggage storage areas, such as overhead and vertical luggage racks, luggage containers and compartments; driver's desk applications, such as paneling and surfaces of driver's desk; interior surfaces of gangways, such as interior sides of gangway membranes (bellows) and interior linings; window frames (including sealants and gaskets); (folding) tables with downward facing surface; interior and exterior surface of air ducts, and devices for passenger information (such as information display screens). For R1 applications, requirements on smoke density after four minutes measured according to ISO 5659-2 (Ds-4) are Ds-4 values at or below 300 measured at 50 kW/m2 for HL2 and at or below 150 measured at 50 kW/m2 for HL3. Requirements on the maximum average rate of heat emission (MAHRE) measured according to ISO5660-1 are at or below 90 kW/m2 determined at 50 kW/m2 for HL2 and at or below 60 kW/m2 determined at 50 kW/m2 for HL3. Requirements on the critical heat flux at extinguishment (CFE) measured according to ISO 5658-2 are at or above 20 kW/m2 for both HL2 and HL3.
It is exceptionally challenging to manufacture interior articles for trains that meet stringent smoke density standards, heat release standards and/or flame spread standards in addition to other material requirements. It is particularly challenging manufacture articles that meet these standards and that have good mechanical properties, including high stiffness, high strength, good impact, and good processability. Accordingly there remains a need for interior articles for trains, and in particular seat components and claddings that have a combination of low smoke, low heat release, and low flame spread properties. It would be a further advantage if the articles could be rendered low smoke and low heat release without a significant detrimental effect on one or more of material cost, manufacturing ease, and mechanical properties. It would be a still further advantage if the materials could be readily thermoformed or injection molded. It would be a still further advantage if such materials were in compliance with European Railway standard EN-45545, for example, without having a detrimental effect on material cost, ease of manufacture, and mechanical properties.